/**
 * AjLog - The AspectJ based logging facade
 *
 * Copyright (C) 2009 - 2010, Marko Umek. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.ajlog.core.message.segment;

import org.ajlog.core.message.IMessageParserResultCollector;
import org.ajlog.core.message.MessageParser;
import org.ajlog.core.setup.IMessageParserNotifier;
import org.ajlog.core.setup.IStaticLoggingContext;

/**
 * IMessageVariableParser will be used for creating {@link IMessageSegment}
 * instances from the content of a message variable (for example:
 * <code>${var}</code> or <code>${ns:var}</code>) evaluated and added by
 * {@link MessageParser}.
 * 
 * @author Marko Umek
 * 
 * @see IMessageSegment
 * @see MessageParser#parseMessage(String, IMessageParserResultCollector)
 * @see IMessageParserResultCollector#appendVariable(String)
 * 
 */
public interface IMessageVariableParser {
    /**
     * The namespace of message segment parser
     * 
     * @return the namespace or <code>null</code> if no namespace is given.
     */
    public String namespace();

    /**
     * accept returns <code>true</code> if the parser accepts the content of the
     * variable.
     * 
     * @param variableValue
     *            the variable name without namespace
     */
    public boolean accept(String variableValue);

    /**
     * parse is responsible for creating the message segment by parsing the
     * variableValue.
     * 
     * @param variableValue
     *            the variable name without namespace
     * @param context
     *            the static context which is necessary to build an
     *            {@link IMessageSegment}
     * @param notifier
     *            used for notification of special circumstances (like
     *            performance enabled, use result, use exception)
     * 
     * @return the created message segment or <code>null</code>
     */
    public IMessageSegment parse(String variableValue, IStaticLoggingContext context, IMessageParserNotifier notifier);

}
